In view of the recent tendency to speed up the photographic processing of photographic light-sensitive materials, a so-called water-resistant photographic paper utilizing a polyolefin-coated paper as a support has been developed and put to practical use. These water-resistant photographic papers using as a support a paper substrate, both surfaces of which are coated with a polyolefin, a hydrophobic resin, have advantages in that fatigue of the developer can be reduced and the time required for rinsing and drying after development can be greatly shortened, since the support absorbs the developer to a lesser extent. Furthermore, these supports have superior dimensional stability.
However, when compared with photographic images formed with conventional photographic paper materials using a baryta-coated paper as a support, the photographic images formed in photographic paper materials utilizing a polyolefin-coated paper as a support have a disadvantage in that the image density contrast and the degree of whiteness of the white background vary depending on conditions under which the photographic images are observed. That is, under certain conditions, they look as if they were deteriorated. For example, when photographic images on poly-olefin coated paper are looked at, a clear distinction can be observed between the case where they are placed on a white plate and the case where they are placed on a black plate. That is, when the photographic images are placed on the black plate, the entire image looks as if it were blackened, and this is more noticeable in areas with a white background. As a result, it looks as if the image contrast drops and the degree of whiteness of the white background is deteriorated. On the other hand, with photographic images on baryta-coated paper, the above-described phenomenon does not occur or occurs only to a limited extent. Similarly, when photographic images on poly-olefin coated paper are observed not on plates as described above but while they are held in the air, their image contrast looks as if it was reduced, in comparison with photographic images on baryta-coated paper.
The cause of the phenomenon is believed to be due to the light-barrier effect of white pigment incorporated in the polyolefin layer of the support, this polyolefin layer being in contact with a light-sensitive silver halide emulsion layer. In particular, the light-barrier effect is insufficiently obtained since the amount and volume-occupying ratio of the white pigment are small. Therefore, part of light is allowed to pass through the support.
Furthermore, when compared with photographic images formed in conventional photographic paper materials utilizing a baryta-coated paper as a support, photographic images formed in photographic paper materials using a polyolefin-coated paper as a support have the disadvantage that the sharpness is poor. The cause of the poor sharpness is also believed to be due to the light-barrier effect of white pigment incorporated in the polyolefin layer of the support, this polyolefin layer being in contact with a light-sensitive silver halide emulsion layer, which light-barrier effect is obtained only insufficiently since the amount and volume-occupying ratio of the white pigment are small and, therefore, halation occurs in the polyolefin layer.
However, incorporation of a large amount of white pigment in the polyolefin layer to obtain a sufficiently high light-barrier effect is not suitable since this seriously reduces the film-forming properties of polyolefin.
In order to improve the reduction in sharpness among the above-described defects, Japanese Patent Application (OPI) No. 64235/82 (the term "OPI" as used herein means a "published unexamined Japanese patent application) discloses a method in which a hydrophilic colloid layer containing white pigment and a dye capable of being decolored during the process of development is sandwiched between a polyolefin-coated paper support and a light-sensitive silver halide emulsion layer. In accordance with this method, however, the dye is decolored after the process of development and the white pigment alone remains in the hydrophilic colloid layer. Thus, the image contrast still varies depending on the observation conditions and, furthermore, the degree of whiteness is not good.